Antibiotic Prescribing Flashcards Preview

ESA 5 - Pharmacology > Antibiotic Prescribing > Flashcards

Flashcards in Antibiotic Prescribing Deck (55)
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1
Q

What is unique about antimicrobials, compared to other drugs?

A

They target microbial biochemistry, rather than the human host

2
Q

What is the main characteristic of an ideal antibiotic?

A

It has no direct effect on the patient

3
Q

How do antibiotics work to not have a direct effect on the patient?

A

Through a process of selective toxicity, whereby they bind to bacterial macrostructures and inhibit their function or structure

4
Q

What are the potential stages in a bacterias life-cycle that antimicrobials can target?

A
  • DNA synthesis
  • Protein synthesis
  • Cell wall synthesis
5
Q

Give two classes of antibiotics that inhibit DNA synthesis

A
  • Quinolones
  • Folic acid antagonists
6
Q

What is the mechansim of action of quinolones?

A

They inhibit DNA gyrase

7
Q

Give an example of a quinolone

A

Ciprofloxacin

8
Q

What is the mechanism of action of folic acid antagonists?

A

They inhibit the production of DNA precursors

9
Q

Give two examples of folic acid antagonists

A
  • Trimethoprim
  • Sulphonamides
10
Q

Give three classes of antibacterials that inhibit protein synthesis

A
  • Aminoglycosides
  • Macrolides
  • Tetracyclines
11
Q

Give an example of an aminoglycoside

A

Gentamicin

12
Q

Give an example of a macrolide

A

Erythromicin

13
Q

Give two classes of antibiotics that inhibit cell wall synthesis

A
  • Beta-lactams
  • Glycopeptides
14
Q

What is the mechanism of action of beta-lactams?

A

They interfere with the ability to build a cell wall, and so the cell wall becomes leaky

15
Q

Give three examples of beta-lactams

A
  • Penicillins
  • Cephalosporins
  • Carbapenems
16
Q

Give an example of a glycopeptide

A

Vancomycin

17
Q

What are the good reasons to use antibiotics?

A
  • Prevention of infections
  • Therapy of significant bacterial infections
18
Q

What are the categories of antibacterial prophylaxis?

A
  • Peri-operative
  • Short term
  • Long term
19
Q

What would happen to surgery without effective prophylaxis?

A

There would be a significant decrease in the scope of surgery

20
Q

Why is antibiotic prophylaxis required peri-operatively?

A

To prevent surgical site infections

21
Q

Are prophylactic antibiotics given after surgery?

A

No, once the wound is closed, there is no need for further doses (with some exceptions), the majority of surgeries only need one dose to last the duration of the surgery

22
Q

Give an example of when short term prophylactic antibiotics may be necessary

A

For meningitis contacts

23
Q

How long are meningitis contacts given prophylactic antibiotics for?

A

2-3 days

24
Q

Give two examples of where people would require long term antibiotics

A
  • Asplenia
  • Immunodeficiency
25
Q

When are antibiotics used in the therapy of bacterial infections?

A
  • Treatment of culture proven infection
  • Empirical treatment of suspected infection, when reasonable grounds for suspicionm, and difference in moderate/long term outcomes
26
Q

Why is a lot of antibiotic prescribing empirical?

A

Because it can take 24-48hours to wait for bacteriology results

27
Q

What questions should be asked when empirically prescribing antibiotics?

A
  • What is the likely organism?
  • Which antibiotics are likely to be effective
  • Which one is the best choice?
28
Q

What aspects of an infection should be considered when deciding on the most likely organism?

A
  • Anatomical site
  • Duration of illness
  • Past medical history
  • Occupational history
  • Travel history
  • Time of year
  • Age
  • Personal background
  • Anatomical site
29
Q

What information can be considered when deciding the likely susceptibility of an infecting bacteria?

A
  • Community or healthcare onset
  • Severity of infection
  • Baseline rate of resistance
  • Immune status of patient
30
Q

What should be considered when deciding what antibiotic is the best choice?

A
  • Efficacy
  • Cost
  • Administration route
  • Safety
31
Q

What should be considered when determining the safety of an antibiotic?

A
  • Age
  • Toxicity
  • Drug interactions
  • Allergies
  • Pregnancy, breast feeding
  • Organ function
32
Q

Is the toxicity of an antibiotic always the same?

A

No, toxicity may have different severities in different groups of people

33
Q

What are the characteristics of an ideal antibiotic therapy?

A
  • Clean kill of infecting bacteria
  • No effects on the patient
34
Q

What is meant by a ‘clean kill of infecting bacteria’?

A
  • No resistance in any surviving pathogens
  • Minimal impact on non-target commensal organisms
35
Q

What are the potential antibiotic adverse effects?

A
  • Phamacological effects, e.g. toxicities and drug interactions
  • Allergic reactions
  • Impact on normal flora
36
Q

What might be caused by an antibiotics impact on normal flora?

A

Clostridium difficile infection

37
Q

What does therapeutic drug monitoring ensure?

A
  • An adequate dose is being given
  • A non-toxic dose is being given
38
Q

What is therapeutic drug monitoring used with?

A
  • Aminoglycosides, including gentamicin
  • Vancomycin
39
Q

How can antibiotic activity be tested?

A

Disc sensitivity testing

40
Q

What is the genetic basis of antibiotic resistance emergence?

A
  • Chromosomal gene mutation
  • Horizontal gene transfer
41
Q

What happens in chromosomal gene mutation?

A
  • A mutated gene conferring resistance is present in one bacteria
  • Antibiotic is applied, killing all but the resistant bacteria
  • The resistant bacteria divides, producing a population of monoclonal resistant bacteria
42
Q

How does horizontal gene transfer occur?

A
  • A bacteria with a resistance gene carried on a plasmid gives off a pili to another cell, transfering the plasmid
  • The plasmid is integrated into the bacterial DNA
  • When the cell divides, it irreversibly becomes part of the cells DNA
43
Q

What are the mechanisms of antibiotic resistance?

A
  • Antibiotic inactivation
  • Alteration of target site
  • Alteration of metabolic pathways
  • Reduced intracellular antibiotic accumulation
44
Q

Give an example of an antibiotic affected by antibiotic inactivation

A

Beta-lactamase

45
Q

Give an example of a binding site that can be altered in antibiotic resistance

A

Penicillin binding protein

46
Q

Give an example of an alteration of a metabolic pathway that can occur to give antibiotic resistance

A

Para-aminobenzoid acid is normally required by bacteria, but some can use preformed folic acid instead

47
Q

Give two examples of how a reduced intracellular antibiotic accumulation can be achieved

A
  • Active efflux mechanisms
  • Decreased permeability
48
Q

What are the steps in the emergence of antibiotic resistance?

A
  1. Local selection
  2. Clonal dissemination
  3. Global spread
49
Q

How can problems with antibiotic resistance be avoided?

A
  • Antimicrobial stewardship
  • Infection control
50
Q

What are the concepts involved in antimicrobial stewardship?

A
  • Right antibiotic
  • Right time
  • Right dose, frequency, and duration
  • Right route
51
Q

What determines the blood and tissue antibiotic concentrations?

A
  • Administration - oral or intravenous
  • Distribution
  • Elimination/metabolism - renal or hepatic
52
Q

What does successful treatment require in time dependant killing?

A

Prolonged antibiotic presence at the site of infection, but not high concentration

53
Q

What does successful treatment require in concentration dependant killing?

A

High antibiotic concentration at site of infection, but not for long

54
Q

How can bacterial exposure to antibiotics be prevented?

A
  • Minimise risk of infection
  • Monitor and control antibiotic prescribing
55
Q

How can the spread of recognised resistant bacteria be prevented?

A
  • Isolation or cohorting
  • Hand hygiene
  • Decolonisation of patients